Field of the Invention
The present invention relates to a transfer image recording method using an ink jet technique.
Description of the Related Art
In recent years, an ink jet recording method is often employed as an image recording method for outputting, for example, an image produced by a computer or a copy image of printed matter. A printer using an ink jet recording method has various advantages, such as unnecessity of a complicated device configuration, low noise, small running costs, and easiness in size reduction and color printing. The printer using an ink jet recording method has flexibility in size of recording media to which the printer is applicable, from a business card size to a large poster size, and has attracted attention in industrial use. For these reasons, such printers using an ink jet recording method have been on the market with those having small sizes at relatively low costs, and thus, are suitably used as printing machines for, for example, personal computers and digital cameras. An ink jet recording method is applied not only to printers but also to output devices of office automation equipment, such as facsimile machines and copiers, and printing equipment.
As a mainstream application of an ink jet recording method, ink is directly applied onto a recording medium such as paper, fabrics, or plastic sheets based on an image signal so that a character or an image, for example, is printed on the recording medium. Since the ink jet recording method does not need a printing plate, even a small number of printed sheets can be effectively produced. Thus, the ink jet recording method is hopefully expected to be applied to industrial printing. In the application to industrial printing, however, usable recording media might be limited in some cases.
A cause of the limitation in applying the method to recording media is ink absorbency of the recording media. Ink used in the ink jet recording method is in a liquid state at room temperature, and a difference in absorption permeability to ink among recording media can affect the image quality. In particular, in a recording medium having no liquid absorbency and a recording medium having low liquid absorbency, such a phenomena as a bleeding phenomenon in which adjacent ink droplets are mixed and a beading phenomenon in which previously impacted ink droplets are attracted to subsequently impacted ink droplets often occur. In the case of a recording medium having low liquid absorbency, in addition to bleeding and beading, a phenomenon called feathering in which ink permeates the recording medium along fibers therein so that ink is blurred can occur. On the other hand, when liquid absorbency of a recording medium is enhanced, the problems described above are reduced, but ink reaches the back surface of the recording medium so that so-called strike-through of an image can occur. In addition, in the case of using an ink having a high moisture content for a recording medium including cellulose fibers and having high liquid absorbency, a cockling phenomenon in which bonds in cellulose constituting fibers in the recording medium are broken so that flatness of the recording medium is impaired.
As a recording method for solving such problems, there is proposed a transfer recording method employing a transfer technique in which an ink image formed on an intermediate transfer member is transferred onto a recording medium by an external force such as a pressure. In the transfer recording method, first, an ink image is temporarily formed on the intermediate transfer member by an ink jet recording method, and the viscosity of the ink image on the intermediate transfer member is increased together with drying of the ink, or a solvent of the ink image is removed so that the ink is condensed, thereby forming an intermediate image. Thereafter, the ink-applied surface of the intermediate transfer member is superimposed on the recording medium so that a pressure and/or heat acts from an ink-nonapplied surface of the intermediate transfer member, and thereby, the intermediate image is transferred onto the recording medium. In the transfer recording method, ink is not directly applied onto the recording medium, but is applied onto the intermediate transfer member. Thus, neither feathering nor cockling occurs in the intermediate transfer member. Thus, this method is effective for prevention of feathering and cockling occurring in association with a permeation behavior of a liquid ink into the recording medium.
As a recording medium used for color image formation by ink jet recording, plain paper used for an electrophotographic copier or other equipment is often used, in addition to dedicated recording sheets for ink jet. This plain paper is produced by a large number of manufacturers, and thus, even white paper slightly differs in paper quality and color tone among manufacturers. In conventional image formation by ink jet recording, a white part in an image is expressed by a base color of a white recording medium. In recent years, however, since the color tone differs among manufacturers as described above, a white ink has been employed. For example, Japanese Patent Application Laid-Open No. 2005-343049 discloses an ink jet recording device including a first white ink applying means and a second white ink applying means. The first white ink applying means is a means for applying a white ink onto an intermediate transfer member. The second white ink applying means is a means for applying a white ink onto a recording medium before a transfer operation. In this manner, the white ink is applied onto the recording medium by the second white ink applying means, then an image is formed by using a color ink, and then, an intermediate transfer member onto which the white ink has been applied by the first white ink applying means is superimposed on the image so that transfer is performed. In this manner, in the case of using the white ink described above, the transfer recording method can obtain advantages similar to those obtained in the case of using an ink of a color except white described above.
In addition, another technique is proposed for enhancing glossiness of an image by covering an image with a smooth transparent coating in a case where a user wishes to express an image formed on a recording medium as a photo-like image. For such a technique, a transparent ink including no coloring materials has been applied. This transparent ink is applicable not only to a direct recording method but also to a transfer image recording method.